- COAL: Pruitt tried a year ago to repeal a key climate-change regulation of President Barack Obama's administration.

In a resignation letter released to media outlets, Pruitt expressed no regret for any actions he had taken since being tapped by Trump to lead EPA previous year.

During his time as a congressional staffer, Wheeler worked as a senior aide to Republican Sen.

In an email sent out to EPA staffers Thursday night and obtained by the Associated Press, Wheeler said he was honored to take temporary leadership of the agency where he started his Washington career in the early 1990s, as an EPA employee dealing with toxic substances and other matters.

Pruitt had appeared Wednesday at a White House picnic for Independence Day, wearing a red-checked shirt and loafers with gold trim.

"Within the Agency Scott has done an outstanding job, and I will always be thankful to him for this", added Trump, who gave no reason for Pruitt's departure.

"I have accepted the resignation of Scott Pruitt as the Administrator of the Environmental Protection Agency", Trump wrote on Twitter Thursday afternoon, while praising Pruitt's work.

Pruitt's resignation comes after a flood of absurd scandals roiled his leadership of the agency.

"I was elated. Jumping up and down, very excited, it's great", Mink toldCBSN of the moment when she realized that Pruitt had resigned. "That was the position he was originally interested in".

Oil dips in nervous markets with U.S., China on brink…An executive from China's Dongming Petrochemical Group said he expected Beijing to soon impose the tariff on U.S. oil imports. The rally appears to be a "short covering situation - we were down nearly 2% yesterday", said Yawger, Reuters reported .

A former Oklahoma attorney general reported to have close ties to fossil fuel industries, Pruitt had become the focus of multiple investigations in recent months, including by his own agency's inspector general, two other independent federal agencies and by Congress itself. Those groups applauded his departure.

Riccardo Savi/Getty Images for Concordia SummitScott Pruitt has resigned as head of the EPA.

He has also rolled back Obama-era regulations such as fuel efficiency standards for cars and trucks.

Some of the ethics accusations involved jobs for Pruitt's wife.

Scott Dworkin, co-founder of the Democratic Coalition: "Someone needs to make sure Scott Pruitt doesn't smuggle his $43,000 soundproof phone booth out of the EPA offices". He also demanded 24-hour-a-day protection from armed officers, resulting in a swollen 20-member security detail that blew through overtime budgets and racked up expenses of more than $3 million. The same lobbyist also asked Pruitt's chief of staff to see if a family friend of his could be hired by the EPA.

- MINING: The EPA said previous year that it won't require mining companies to prove they have the financial resources to clean up pollution, an Obama-era rule stemming from a long history of pollution spilling from abandoned mines into streams.